1. Field of the invention
This invention relates to improvements in a biomedical material for curing a bone defect or the like of human beings or animals, and more particularly to such a biomedical material including hydroxylapatite beads and/or flakes in order to make possible an early and nearly complete cure for the bone defect or the like.
2. Description of the Prior Art
Hitherto some biomedical materials for curing the bone defect or the like of human beings and animals have been proposed and put into practical use, as set forth below.
&lt;First conventional technique&gt;
Hydroxylapatite powder is fabricated into a variety of shapes and then fired to be solidified thereby to obtain a biomedical material applied to the bone defect of a variety of sizes and shapes. Otherwise, irregularly shaped hydroxylapatite power is mixed with a binder such as a biodegradable polymer or acid and then solidified to obtain a biomedical material.
&lt;Second conventional technique&gt;
Hydroxylapatite powder is mixed with the binder such as the biodegradable polymer or acid to form a hydroxylapatite paste as a biomedical material. The thus formed paste is flowable and therefore well fittable to a variety of shapes of bone defects.
However, drawbacks have been encountered in the above-discussed first and second conventional techniques, as set forth below. Concerning the first conventional technique, the biomedical material has been solidified to take a certain shape before use for curing the bone defect. Accordingly, even if a variety of shapes of such conventional biomedical materials are prepared, it is very difficult to effectively and uniformly disperse the biomedical material throughout, for example, an irregularly shaped bone defect or an irregular shaped space between the surface of a bone defect and an implant in case of cure using an implantation. As a result, according to this first conventional technique, a cure for the bone defect usually requires a time period of several months to more than 1 year.
Concerning the second conventional technique, this is advantageous and seems slightly advanced over the first conventional technique in a point at which the hydroxylapatite paste can be filled to be fittable to the irregularly shaped bone defect. However, since the biomedical material formed from the hydroxylapatite paste is not porous, it is small in specific surface area and insufficient in amount of circulation of blood through the biomedical material. As a result, bone conduction or new bone formation is obstructed or retarded not only in a deep portion of the biomedical material but also in a surface portion of the same. This lowers the inherent effect of bone formation of the biomedical material, so that a cure for the bone defect requires several months.